Image-processing apparatus, image-processing method and recording medium

ABSTRACT

In an image-processing apparatus, a digital image signal is stored in a memory, and a memory access control part entirely manages all accesses to the memory with respect to the digital image signal. An image processing part converts the digital image signal stored in the memory into an output image signal to be supplied to an imaging unit outputting a visible image based on the output image signal so that a pixel density of the output image signal is higher than a pixel density of the digital image signal read from the memory and an amount of the output image signal is less than an amount of the digital image signal stored in the memory. Accordingly, the central controlled memory is shared by a plurality of functions so as to effectively use the memory, and a high-quality image can be produced by carrying out a density conversion so as to match the pixel density.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention generally relates to image processingapparatuses and, more particularly, to an image-processing apparatuswhich converts read image into recordable image signal after changingthe read image to digital image signals.

[0003] 2. Description of the Related Art

[0004] Conventionally, multi-function apparatuses provided with aplurality of functions, such as a so-called copy function includingreading of an image, a record output or transmission and reception ofimage data, a facsimile function, a printer function, a scannerfunction, etc., are known. A conventional multi-function apparatus (MFP)100 shown in FIG. 1 comprises a facsimile control unit (FCU) 101, aprinter control unit (PCU) 102, a motherboard 103, a reading unit 104,an image-processing unit 105, a video control part 106, an imaging unit107, a memory control unit 108, a system controller 109, a random accessmemory (RAM) 110 and a read only memory (ROM) 111. The PCU 102comprises, as shown in FIG. 2, a memory access control part (IMAC) 121,a network interface (I/F) 122, a system controller 123, a local businterface (I/F) 124, a parallel bus interface (I/F) 125, a memory group(MEM) 126 and a serial bus interface (I/F) 127.

[0005] In the multi-function apparatus (MFP) 100, after the reading unit104 optically reads an image of an original and changes the read imageinto a digital image signal, the reading unit 104 outputs the digitalimage signal to the image-processing unit 105. The imaging unit 107forms a reproduction image on a transfer paper based on the digitalimage signal from the video bus control part 106.

[0006] The image-processing unit 105 applies various image qualityprocesses, such as correction of image degradation in the reading systemof the reading unit 104 and gradation reproduction by an area gradationmethod, to the image signal, and outputs the processed image signal tothe video control part 106. The video control part 106 performs a buscontrol, and arbitrates an incoming signal from the image-processingunit 105, an output signal to the imaging unit 107, an input-and-outputsignal to the memory control unit 108, and an input-and-output signalwith the FCU 101 and the PCU 102 which are external application unitsconnected through the motherboard 103.

[0007] An external extension application unit can connect a plurality ofapplications to the motherboard 103. Each application has a CPU and amemory, and functions as an independent unit. For example, the FCU(facsimile control unit) 101 and the PCU (printer control unit) 102correspond to the applications. Regarding the job using a memory, suchas image rotation by the copy function, after the MFP 100 stores theimage data from the image-processing unit 105 in the memory control unit108 via the video control part 106 and performs image rotationprocessing, the MFP 100 carries out image reproduction in the imagingunit 107 via the video control part 106. The MFP 100 carries out theseries of controls by the system controller 109. On the other hand,regarding a deployment process on the memory of the printer output imageby the PCU 102, the system controller 109 and the memory control unit108 do not use the MFP 100, but uses uniquely the system controller 124and the memory group 126 provided in the PCU 102 shown in FIG. 2.

[0008] In the PCU 102 shown in FIG. 2, the system controller 124controls an operation of the entire PCU 102 so that the PCU 102 operatesas a single unit as a whole. That is, the memory which can be used bythe PCU 102 is only the memory group 126 inside the PCU 102. Such acomposition of the PCU 102 is the same as the FCU 101. If data is sentto the PCU 102 via a network, print output request data is taken in theIMAC 121 through the network I/F 122.

[0009] When a general-purpose serial bus connection is used, the systemcontroller 123 receives the print output request data supplied to theIMAC 121 via the serial bus I/F 127. Usually, a plurality of kinds ofinterfaces are provided as the general-purpose serial bus I/F 127 so asto cope with interfaces such as USB, IEEE1284 and IEEE1394. The systemcontroller 123 develops the received print output request data to imagedata in an area within the MEM 126. At this time, font data of a fontROM (not illustrated in the figure) connected to the local bus concernedis referred to via the local bus I/F 124 and a local bus.

[0010] A serial bus connected to the serial bus I/F 127 is also providedwith an interface (I/F) for data transmission with an operation part ofthe MFP 100 in addition to an external serial port for connection with apersonal computer. Unlike print deployment data, the operation part ofthe MFP 100 communicates with the system controller 123 via the IMAC121.

[0011] The system controller 123 controls reception of the processingprocedure from the operation part and the display of the state of thesystem on the display part. The local bus connected to local bus I/F 124is connected to the ROM and RAM required for control of the controllerunit. Font data is input through the local bus and used for imagedeployment.

[0012] In the above-mentioned conventional multi-function apparatus(MFP), a memory is not used effectively and communization of a controlmechanism including extended units is not made. That is, each of thefacsimile control unit (FCU) and the printer control unit (PCU) hasindividually a system control module, a memory module and a memorycontrol module. Accordingly, each control unit performs a similarcontrol separately, and, thereby, effective use of resources is notachieved. Therefore, the apparatus is enlarged, and a cost is increased.Moreover, it is necessary to improve for increasing a processing speed.

[0013] Moreover, in the above-mentioned multi-function apparatus (MFP),in order to realize a high-quality image by a high-densification ofdots, it has been suggested to perform a dot position control ofwriting. This is for the reason that a single dot reproduction withhigh-density dots needs a high technology, and, on the other hand, astable and smooth gradation can be obtained by concentrating dots.However, depending on the kind of image, a very thin line, for example,is crushed when dots are concentrated. In such a case, it is necessaryto perform a signal processing to cause a single isolated dotreproduced.

[0014] On the other hand, it has been suggested to attain a high qualityoutput image by performing writing with a higher density than a readingdensity. For example, a process has been suggested to read by 600 dpiand write by 1200 dpi. If a single pixel of 600 dpi is converted intofive values by halftone processing, the pixel data becomes 33-bit data.If this data is converted into a binary value of 1200 dpi by ahigh-density conversion, the data becomes 4-bit data. That is, an amountof image data increases by the high-densification conversion.Furthermore, when information of the above-mentioned pixel arrangementis added, the amount of information increases further and there is aproblem in that a processing speed is decreased. Japanese Laid-OpenPatent Application No. 6-12112 discloses a technology to reduce anamount of data by encoding image data. However, the technology disclosedin Japanese Laid-Open Patent Application No. 6-12112 relates to anexchange of image data with external equipment, such as a printer or afacsimile machine, and does not relate to encoding of high-density datafor data transmission inside a processing apparatus.

SUMMARY OF THE INVENTION

[0015] It is a general object of the present invention to provide animage processing apparatus and method in which the above-mentionedproblems are eliminated.

[0016] A more specific object of the present invention is to provide animage-processing apparatus and method in which a central-controlledmemory is shared by a plurality of functions so as to effectively usethe memory.

[0017] Another object of the present invention is to provide animage-processing apparatus and method which is inexpensive and small andcan produce a high-quality image by carrying out a density conversion soas to match the pixel density.

[0018] A further object of the present invention is to provide animage-processing apparatus and method and a recording medium storing aprocess program to carry out the image-processing method, which canefficiently perform data processing by encoding high-density data withinthe image-processing apparatus.

[0019] In order to achieve the above-mentioned objects, there isprovided according to one aspect of the present invention animage-processing apparatus comprising: a memory storing a digital imagesignal; a memory access control part entirely managing all accesses tothe memory with respect to the digital image signal; and an imageprocessing part converting the digital image signal stored in the memoryinto an output image signal to be supplied to an imaging unit outputtinga visible image based on the output image signal so that a pixel densityof the output image signal is higher than a pixel density of the digitalimage signal read from the memory and an amount of the output imagesignal is less than an amount of the digital image signal stored in thememory.

[0020] According to the above-mentioned invention, the centralcontrolled memory is shared by a plurality of functions so as toeffectively use the memory, and a high-quality image can be produced bycarrying out a density conversion so as to match the pixel density.Additionally, the image-processing apparatus according to the presentinvention is inexpensive and small and can effectively use resources.

[0021] The image-processing apparatus according to the present inventionmay further comprise a programmable operation processor processing thedigital image signal so as to reduce a number of quantization steps ofthe digital image signal and store the digital image signal having areduced number of quantization steps in the memory. Accordingly, anarbitrary image processing can be applied to the read image data so asto improve the image quality and also the data transmission efficientcan be improved.

[0022] Additionally, the memory access control part may arrange pixelsof the output image signal in a square area while preventing generationof an isolated single pixel of black or white when converting thedigital image data into the output image data. Accordingly, the numberof pixels can be increased in both the main scanning direction and thesubscanning direction at the same time, which results in a highefficiency pixel-density conversion.

[0023] Further, the memory access control part may include a pixeldensity conversion part converting the digital image signal by using thememory; and the image processing part may include an edge smoothing partsmoothing an edge of black pixels and white pixels, wherein the edgesmoothing part is controlled, separately from the pixel densityconversion part, by a write-in control performed by the imaging unit.Accordingly, the smoothing process depending on the characteristics ofthe imaging unit and the pixel-density conversion are performedindependently from each other so as to reduce a processing time of thepixel-density conversion. Thus, a further higher-quality image can beproduced for a short time.

[0024] Additionally, the output image signal may be transmitted from thememory to the imaging unit in a form of code data, and the imaging unitmay convert the code data into pixel data so as to perform an imageoutput under the write-in control of the imaging unit. Accordingly, Thedata transmission from the memory to the imaging unit can be effectivelyperformed in a short time, and the data bus is effectively used. Thus, afurther efficient processing can be performed at a high speed.

[0025] Additionally, transmission of the code data from the memory tothe imaging unit is performed in synchronization with a signalindicating a write-in line of the code data. Accordingly, the image datacan be transmitted only when it is needed in accordance with a requestby the imaging unit. Thus, a bus occupancy time can be reduced, whichimproves a total efficiency of memory use and bus use.

[0026] Additionally, there is provided according to another aspect ofthe present invention an image-processing method comprising the stepsof: storing a digital image signal in a memory; entirely managing allaccesses to the memory with respect to the digital image signal; andconverting the digital image signal stored in the memory into an outputimage signal to be supplied to an imaging unit outputting a visibleimage based on the output image signal so that a pixel density of theoutput image signal is higher than a pixel density of the digital imagesignal read from the memory and an amount of the output image signal isless than an amount of the digital image signal stored in the memory.

[0027] According to the above-mentioned invention, the centralcontrolled memory is shared by a plurality of functions so as toeffectively use the memory, and a high-quality image can be produced bycarrying out a density conversion so as to match the pixel density.Additionally, the image-processing apparatus according to the presentinvention is inexpensive and small and can effectively use resources.

[0028] Additionally, there is provided according to another aspect ofthe present invention a processor readable medium storing program codefor causing an image-processing apparatus to perform an imageprocessing, comprising: program code means for storing a digital imagesignal in a memory; program code means for entirely managing allaccesses to the memory with respect to the digital image signal; andprogram code means for converting the digital image signal stored in thememory into an output image signal to be supplied to an imaging unitoutputting a visible image based on the output image signal so that apixel density of the output image signal is higher than a pixel densityof the digital image signal read from the memory and an amount of theoutput image signal is less than an amount of the digital image signalstored in the memory.

[0029] According to the above-mentioned invention, the centralcontrolled memory is shared by a plurality of functions so as toeffectively use the memory, and a high-quality image can be produced bycarrying out a density conversion so as to match the pixel density.Additionally, the image-processing apparatus according to the presentinvention is inexpensive and small and can effectively use resources.

[0030] Additionally, there is provided according to another aspect ofthe present invention an image-processing apparatus having a framememory controlled by a memory controller, comprising: a scanner readingan image so as to produce read image data; a pixel density conversionpart converting the read image data into high-density image data havinga pixel density higher than a pixel density of the read image data; amemory storing the high-density image data according to a predeterminedarrangement of pixels; a code conversion part converting thehigh-density image data into code data according to a predeterminedconversion code; and an output interface part outputting code data asimage data to an imaging unit forming a visible image based on the imagedata.

[0031] According to the above-mentioned invention, since thehigh-density imaged data is transmitted by reducing the amount of databy encoding, the data transmission efficiency is improved and ahigh-speed image processing can be achieved.

[0032] In the image-processing apparatus according to theabove-mentioned invention, the code conversion part may decide an ON/OFFposition of pixel data of the image data output from the outputinterface part, and the output interface part may change pixel positionsof the high-density image data based on pixel positions of the readimage data. Accordingly, a dot control matching the characteristics ofan image can be performed with a reduced amount of data, and ahigh-quality image can be produced.

[0033] Additionally, the code conversion part may set the pixelpositions of the high-density image data based on information regardingcharacteristics of the read image data. Accordingly, a dot controlmatching the characteristics of an image can be performed with a reducedamount of data, and a high-quality image can be produced.

[0034] There is provided according to another aspect of the presentinvention an image-processing method comprising the steps of: reading animage so as to produce read image data; converting the read image datainto a high-density image data having a pixel density higher than apixel density of the read image data; storing the high-density imagedata in a memory according to a predetermined arrangement of pixels;converting the high-density image data into code data according to apredetermined conversion code; and outputting code data as image data toan imaging unit forming a visible image based on the image data.

[0035] According to the above-mentioned invention, since thehigh-density imaged data is transmitted by reducing the amount of databy encoding, the data transmission efficiency is improved and ahigh-speed image processing can be achieved.

[0036] In the image-processing method according to the above-mentionedinvention, the step of converting the high-density image data mayinclude a sep of deciding an ON/OFF position of pixel data of the imagedata, and the step of outputting code data may include a step ofchanging pixel positions of the high-density image data based on pixelpositions of the read image data.

[0037] Additionally, the step of converting the high-density image datamay include a step of setting the pixel positions of the high-densityimage data based on information regarding characteristics of the readimage data.

[0038] There is provided according to another aspect of the presentinvention, a processor readable medium storing program code for causingan image-processing apparatus to perform an image processing,comprising: program code means for reading an image so as to produceread image data; program code means for converting the read image datainto a high-density image data having a pixel density higher than apixel density of the read image data; program code means for storing thehigh-density image data in a memory according to a predeterminedarrangement of pixels; program code means for converting thehigh-density image data into code data according to a predeterminedconversion code; and program code means for outputting code data asimage data to an imaging unit forming a visible image based on the imagedata.

[0039] According to the above-mentioned invention, since thehigh-density imaged data is transmitted by reducing the amount of databy encoding, the data transmission efficiency is improved and ahigh-speed image processing can be achieved.

[0040] In the processor readable medium, the program code means forconverting the high-density image data may include program code meansfor deciding an ON/OFF position of pixel data of the image data, and theprogram code means for outputting code data may include program codemeans for changing pixel positions of the high-density image data basedon pixel positions of the read image data.

[0041] Additionally, the program code means for converting thehigh-density image data may include program code means for setting thepixel positions of the high-density image data based on informationregarding characteristics of the read image data.

[0042] Other objects, features and advantages of the present inventionwill become more apparent from the following detailed descriptions whenread in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043]FIG. 1 is a block diagram of a conventional multi-functionapparatus;

[0044]FIG. 2 is a block diagram of a printer control unit shown in FIG.1;

[0045]FIG. 3 is a circuit block diagram of a multi-function apparatus(MFP) according to a first embodiment of the present invention;

[0046]FIG. 4 is a block diagram of an image memory access control part(IMAC) shown in FIG. 3;

[0047]FIG. 5 is a block diagram of a memory control part shown in FIG.4;

[0048]FIG. 6 is a block diagram of a video data control part (VDC) shownin FIG. 3;

[0049]FIG. 7 is an illustration for explaining a switching control ofupper pixels or lower pixels decoded in a selector in the VDC shown inFIG. 6;

[0050]FIG. 8 is an illustration showing a system control and a busconnection in a basic structure of the MFP shown in FIG. 3;

[0051]FIG. 9 is an illustration showing the system control and the busconnection of the MFP in a printer mode;

[0052]FIG. 10 is an illustration showing a control bus connection of theMFP shown in FIG. 3;

[0053]FIGS. 11A is an illustration showing a data compressing operationof the IMAC shown in FIG. 4; and FIG. 11B is an illustration showing adata decompressing operation of the IMAC shown in FIG. 4;

[0054]FIG. 12A, 12B and 12C are is illustrations for explaining a pixeldensity conversion process applied to read image data by the MFP shownin FIG. 3;

[0055]FIG. 13 is an illustration for explaining an example of a codeassignment by the MFP shown in FIG. 3;

[0056]FIG. 14 is an illustration for explaining an example of a codeconversion shown in FIG. 13;

[0057]FIG. 15 is a block diagram showing data transmission paths of readimage data when a pixel density conversion process is performed by theMFP shown in FIG. 3;

[0058]FIG. 16 is a block diagram showing data transmission paths ofbinary value image data when a pixel density conversion process isperformed by the MFP shown in FIG. 3;

[0059]FIG. 17 is a block diagram of a frame memory and a memory accesscontrol part (IMAC) in an image processing apparatus according to asecond embodiment of the present invention;

[0060]FIG. 18 is an illustration for explaining an operation of ahigh-density conversion part of the IMAC shown in FIG. 17;

[0061]FIG. 19 is an illustration of an example of an operation performedby a code conversion part of the IMAC shown in FIG. 17;

[0062]FIG. 20 is an illustration of another example of the operationperformed by the code conversion part of the IMAC shown in FIG. 17;

[0063]FIG. 21 is a block diagram of the IMAC and other peripheral partsconfigured to perform an operation to change pixel positions; and

[0064]FIG. 22 is an illustration showing an example of data development.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0065] A description will now be given, with reference to accompanyingdrawings, of preferred embodiments of the present invention.

First Embodiment

[0066]FIG. 3 through FIG. 16 show an image-processing apparatus andmethod and a recording medium according to a first embodiment of thepresent invention. FIG. 3 is a circuit block diagram of a multi-functionapparatus (MFP) 1 according to the first embodiment of the presentinvention.

[0067] In FIG. 3, the MFP 1 comprises: a reading unit 2; a sensor boardunit 3 (SBU); a compression/decompression and data interface controlpart (CDIC) 4; an image-processing processor (IPP) 5; a video datacontrol part (VDC) 6; an imaging unit 7, a process controller 8; arandom access memory (RAM) 9; a read only memory (ROM) 10; a facsimilecontrol unit (FCU) 11; an image memory access control part 12 (IMAC); amemory group (MEM) 13; a system controller 14; an operation panel 15; anexternal serial port 16; a RAM 17; a ROM18; and a font ROM 19. Thereading unit 2, the SBU 3, the CDIC 4, the IPP 5, the VDC 6, the imagingunit 7, the process controller 8, the RAM 9 and the ROM 10 are connectedto the serial bus 20. The FCU 11, the IMAC 12, the CDIC 4 and the VDC 6are connected to the parallel bus 21. Moreover, the IMAC 12, the RAM 17,the ROM18, and the font ROM 19 are connected to the local bus 22.

[0068] The MFP 1 has various mode functions, such as a scanner mode, acopy mode, a facsimile mode, and a printer mode. In the scanner mode orcopy mode of the MFP 1, a reading unit 2 irradiates a reading light froma light source onto an original and a light-receiving elements, such asa charge coupled device (CCD), which SBU 3 provided through the mirrorand the lens, condense the catoptric light from an original. In thescanner mode or copy mode of the MFP 1, the reading unit 2 irradiates areading light from a light source onto an original, and converges thereading light reflected by the original onto a light-receiving element,such as a charge coupled device (CCD) provided to the SBU 3, via amirror and a lens. By carrying out an optoelectric conversion by thelight-receiving element concerned so as to read the original in aprimary scanning direction, a digital conversion of the image signal iscarried out by the SBU 3 so as to produce and outputs the digital imagesignal to the CDIC 4.

[0069] The CDIC 4 controls all transmissions of image data between afunctional device and a data bus, and performs data transmission betweenthe SBU 3, the parallel bus 21 and the IPP 5. Moreover, the CDIC 4performs communication between the system controller 14, which controlsthe entire MFP 1, and the process controller 8, which performsprocessing control to image data. The CDIC 4 transfers the image signalfrom the SBU 3 to the IPP 5, and the IPP 5 corrects a signal degradation(signal degradation of a scanner system) in the optical system and thataccompanying the quantization to an optical system. The IPP 5 outputsthe image signal to the CDIC 4 again.

[0070] In the image processing, the MFP 1 has a job to accumulate andreuse image data (read image data etc.) in a memory and a job which iscarried out without accumulating image data in a memory. In an exampleof the job to accumulate image data in a memory, the reading unit 2 isoperated only once, when copying a plurality of originals, so as tostore the image data in the memory, the image data is used a pluralityof times by reading the image data stored in the memory. As an examplewithout using a memory, there is a case in which only one copy of oneoriginal is carried out, for example. In this case, since what isnecessary is just to reproduce read image data as it is, it is notnecessary to perform a memory access.

[0071] When not using a memory, the MFP 1 returns the data, which hasbeen transmitted to the CDIC 4 from the IPP 5, to the IPP 5 from theCDIC 4 as mentioned above. The IPP 5 performs an image qualityprocessing for converting luminance data of a light-receiving elementinto area gradation data. The IPP 5 transmits the image data after beingsubject to the image quality processing to the VDC 6. The VDC 6 performsa pulse control with respect to the signal which has been changed to thearea gradation data so as to perform a post-processing on a dotarrangement and reproduce dots. In the imaging unit 7 as a writingmeans, a reproduction image is formed on a transfer paper. As an imagingunit 7, although units of various record systems can be used, a unit ofan electrophotography system is used, for example.

[0072] When performing an additional processing, for example, rotationof an image orientation, synthesis of an image, etc. by using a memory,the MFP 1 sends the data, which has been transmitted to the CDIC 4 fromthe IPP 5, from the CDIC 4 to the IMAC 12 via the parallel bus 21. TheIMAC 12 performs an access control of the image data and the MEM 13under a control of the system controller 14. Moreover, the IMAC 12develops the print data of the externally connected personal computer(PC) 30. Furthermore, the IMAC 12 performs compression/decompression ofthe image data for effectively using the memory. Namely, the PC 30 isconnected to the IMAC 12, and under control of the system controller 14,the IMAC 12 receives the digital print data of the PC 30 and developsthe print data on the MEM 13. After the IMAC 12 carries out the datacompression of the data, the IMAC 12 accumulates the compressed data tothe MEM 13. Moreover, after decompressing the accumulated data, which isread from the MEM 13 when it is needed, the decompressed data istransferred to the CDIC 4 via the parallel bus 21. The MFP 1 transmitsthe data transferred to the CDIC 4 to IPP 5 from the CDIC 4, and causethe IPP 5 to perform the image quality processing for converting theluminance data of the light-receiving element into area gradation data.The IPP 5 transmits the image data after image quality processing to theVDC 6, and performs a pulse control on the signal which has been changedto the area gradation data by the VDC 6 for the post-processingregarding the dot arrangement and reproducing dots. Then, the IPP 5forms a reproduction image on the transfer paper in the imaging unit 7.That is, by a bus control of the parallel bus 21 and the CDIC 4, the MFP1 performs accumulation of data to MEM13 and various transmissionprocessings of data so as to achieve the function as the MFP 1.

[0073] Moreover, the public line (PN) 31 is connected to the FCU 11. TheMFP 1 realizes facsimile transmission and reception function byutilizing the FCU 11. That is, the MFP 1 transmits the image data readby the reading unit 2 to the IPP 5 as mentioned above at the time offacsimile transmission. The image data is transmitted to the FCU 11 viathe CDIC 4 and the parallel bus 21, after a required image processing isperformed in the IPP 5. The FCU 11 performs data conversion to acommunications network, and transmits the data to the PN 31 as facsimiledata. At the time of facsimile reception, the MFP 1 converts thefacsimile data, which is transmitted from the PN 31 and received by theFCU 11, into image data, and transmits the image data to the IPP 5 viathe parallel bus 21 and the CDIC 4. In this case, the IPP 5 does notperform any special image quality processing on the transmitted imagedata, but transmits the received image data to the VDC 6. Then, dotrearrangement and pulse control are performed by the VDC 6, and areproduction image is formed on the transfer paper in the imaging unit7. The system controller 14, the operation panel 15, and the externalserial port 16, etc. are connected to the IMAC 12. The system controller14 controls the whole MFP 1. Various keys, a display part, etc. areprovided in the operation panel 15 so as to perform various instructingoperations to the MFP 1. The system controller 14 performs a basicprocessing as the MFP 1 and a memory control process processing bycontrolling each part of the MFP 1 according to instructing operationsthrough the operation panel 15. Moreover, the MFP 1 has a function toconcurrently perform a plurality of jobs such as a copy function, afacsimile transceiver function, a printer output function, etc. Whenprocessing a plurality of jobs in parallel, the right to use the readingunit 2, the imaging unit 7, and the parallel bus 21 is assigned to thejobs. This assignment is controlled by the system controller 14 and theprocess controller 8.

[0074] The process controller 8 controls a flow of the image data. Thesystem controller 14 controls the whole system of the MFP 1, and managesactivation of each resource. A selection of function of the MFP 1 isperformed by a key operation of the operation panel 15. The contents ofprocessing, such as a copy function or a facsimile transceiver function,are set up by the key operation of the operation panel 15.

[0075] The system controller 14 and the process controller 8 communicatemutually through the parallel bus 21, the CDIC 4 and the serial bus 20so as to perform a data format conversion for the data interface betweenthe parallel bus 21 and the serial bus 20 in the CDIC 4.

[0076] As shown in FIG. 4, the IMAC 12 comprises an access control part41, a system I/F 42, a local bus control part 43, a memory control part44, a compression/decompression part 45, an image editorial part 46, anetwork control part 47, a parallel bus control part 48, a serial portcontrol part 49, a serial port 50 and direct memory access control parts(DMAC) 51-55. The direct memory access control parts (DMAC) 51-55 areprovided between the access control part 41 and each of thecompression/decompression part 45, the image editorial part 46, thenetwork control part 47, the parallel bus control part 48 and the serialport control part 49.

[0077] The IMAC 12 is connected to the system controller 14 through thesystem I/F 42 so as to perform transmission and reception of commandsand data with the system controller 14 through the system I/F 42. Asmentioned above, the system controller 14 basically controls the entireoperation of the MFT 1. The resource allocation of the memories of thememory group 13 is also under management of the system controller 14.Control of operations of other units is performed in the parallel bus 21through the system I/F 42 and the parallel bus control part 48.

[0078] Each unit of the MFP 1 is fundamentally connected to the parallelbus 21, and the data transmission and reception to the system controller14 and the memory group 13 are managed by the parallel bus control part48 controlling bus occupancy.

[0079] The network control part 47 is connected to a predeterminednetwork NW such as a local area network (LAN). The network control part47 controls connection with the network NW, and manages datatransmission and reception with external extension devices connected tothe network NW. The system controller 14 is not involved in themanagement of operations of the extension devices connected to thenetwork NW. The system controller 14 controls the interface on the sideof the IMAC 12. In addition, the control with respect to 100BT is addedin the present embodiment. The IMAC 12 interfaces the connection withthe serial bus 20 through a plurality of serial ports 50, and has portcontrol mechanisms corresponding to the number of kinds of busses.Namely, the IMAC 12 has the serial ports whose number corresponds to thenumber of kinds of busses such as, for example, USB, IEEE1284 andIEEE1394. The serial port control part 49 performs controls of thoseports. Moreover, the serial port control part 49 controls, separatelyfrom the external serial port 50, the data transmission and receptionwith the operation panel 15 with respect to reception of commands anddisplay.

[0080] The local bus control part 43 interfaces with the RAM 17 and theROM 18, which are needed to activate the system controller 14, and alsointerfaces with the local (serial) bus 22 to which the font ROM 19 whichdevelops printer code data is connected. The memory control part 44 isconnected with the MEM 13 so as to interfaces with the MEM13.

[0081] The access control part 41 controls operations by carrying out acommand control sent from the system controller 14 through the systemI/F 42. Moreover, the access control part 41 performs data controlcentering on the MEM 13 by managing a memory access from an externalunit. That is, the image data to the IMAC 12 from the CDIC 4 istransmitted through the parallel bus 21, and is taken in the IMAC 12 bythe parallel bus control part 48. The image data taken in the IMAC 12leaves management of the system controller 14 in the DMAC 54. Thereby,memory access is performed independently from the system control. Theaccess control part 41 arbitrates the access to the MEM 13 from aplurality of units. The memory control part 44 controls an accessoperation and a data reading and writing operation to the MEM13.

[0082] Moreover, in the IMAC 12, an access from the network NW to theMEM 13 is also performed by accessing the MEM 13 through the DMAC 53with the data taken in the IMAC 12. Then, the access control part 41arbitrates accesses to the MEM 13 in a plurality of jobs, and the memorycontrol part 44 performs reading/writing of data.

[0083] Furthermore, the IMAC 12 performs an access to the MEM 13 fromthe serial bus 20 by accessing the data taken in the IMAC 12 through theserial port 50 by the serial port control part 49 by the DMAC 55. TheIMAC 12 arbitrates accesses to the MEM 13 in a plurality of jobs in theaccess control part 41, and performs reading/writing of data in thememory control part 44. Then, in the MFP 1, if the print data of the PC30 is sent from the network NW or the serial bus 20, the systemcontroller 14 develops print data in the memory area of the MEM 13 usingthe font data of the font ROM 19 on the local bus 22.

[0084] In MFP 1, the system controller 14 manages an interface with eachexternal unit. Then, each DMAC 51-55 in the IMAC 12 manages memoryaccess. In this case, since each DMAC 51-55 performs data transmissionindependently, the access control part 41 performs priority attachmentwith respect to the collision of jobs and each access request withrespect to the access to the MEM 13. Accesses to the MEM 13 include anaccess of the system controller, other than the accesses by each DMAC51-55, through the system I/F 42 for bit map deployment of stores data.The data of DMAC to which the access control to the MEM 13 is permitted,or the data from the system I/F 42 is performed by a direct access tothe MEM 13 by the memory control part 44.

[0085] The IMAC 12 performs a data processing by thecompression/decompression part 45 and the image editorial part 46. Thatis, the compression/decompression part 45 performs a compression and adecompression of data by a predetermined compression system so as toaccumulate image data or code data efficiently to the MEM 13. The datacompressed by the compression/decompression part 45 is stored in MEM 13by the DMAC 51-55 controlling an interface with the MEM 13.

[0086] The IMAC 12 transmits the data once stored in the MEM 13 to thecompression/decompression part 45 through the memory control part 44 andthe access control part 41 by a control of the DMAC. Then, afterdecompressing the compressed data, the IMAC 12 performs a control suchas returning to the MEM 13 or outputting to an external bus.

[0087] The image editorial part 46 controls the MEM 13 by the DMAC 51-55so as to clear the memory area in the MEM 13 and perform a dataprocessing such as a rotation of an image or a synthesis of differentimages. Moreover, the image editorial part 46 performs an addresscontrol on the memories of the MEM 13 so as to convert the data to beprocessed. However, the image editorial part 46 does not perform aconversion of code data after being compressed by thecompression/decompression part 45, or conversion into printer code butperforms the above-mentioned image processing on a bit map imagedeveloped on the MEM 13. That is, the compression process foraccumulating data effectively to the MEM 13 is performed after an imageedit is performed by the image editorial part 46. The memory controlpart 44 comprises, as shown in FIG. 5, a data path control part 61, thedata buffer 62, a request control part 63, an input-and-output controlpart 64, an output I/F 65, an input I/F 66, an external memory accesscontrol part 67 and a command control part 68. The memory control part44 transmits and receives data between the access control part 41 andthe MEM 13.

[0088] The access control part 41 has an interface with each DMAC 51-55.The access control part 41 receives the command for the intervention tothe MEM 13 of the system controller 14 to the MEM 13 and accessarbitration by being connected to the system I/F 42. Thereby, an accessto the MEM 13 is independently attained for the access request to theMEM 13 of the DMACs 51-55 and the system controller 14. Therefore,reading from the MEM 13 and the writing to MEM 13 are attained.Moreover, the access control part 41 judges a priority provided from thesystem controller 14 with respect to a plurality of competing readrequests or write requests, and switching a path to the memory controlpart 44 and the access control part 41 by a command control from thesystem controller 14.

[0089] Since data maintenance cannot be performed on the DMAC 51-55which is not permitted to write in the MEM 13, data input from outsidecannot be performed, and, therefore, a data input operation of externalunits is prohibited by a control of the system controller 14.

[0090] Output data of the DMAC 51-55 or the system I/F 42 of whichaccess to the MEM 13 is permitted is transmitted to the memory controlpart 44. Moreover, a command of the permitted system controller 14 isalso transmitted to the memory control part 44.

[0091] The memory control part 44 temporarily stores in the data buffer62 the data transmitted from the access control part 41. The data pathcontrol part 61 switches a path to the output I/F 65 to the MEM 13. Thememory control part 44 performs the control of the path by decoding thecommand by the system I/F 42 and activating the access of the output I/F65 to the MEM 13 by the input-and-output control part 64.

[0092] The memory control part 44 generates a MEM control signal by theexternal memory access control part 67 based on control system data sentfrom the DMACs 51-55 or the system controller 14 so a to perform anaddress control of the MEM 13. The memory control part 44 transmits thedata and the MEM control signal to the MEM 13, and stores the data inthe MEM 13. The memory control part 44 reads the data stored in the MEM13. That is, based on the control system data from the DMAC 51-55 or thesystem controller 14 to which an access to the MEM 13 is permitted, thememory control part 44 generates the MEM control signal by the externalmemory access control part 67, and performs an address control of theMEM 13. Then, the memory control part 44 transmits a control signal tothe MEM 13 from the external memory access control part 67, and performsa memory read-out processing, and taken in the access data through theI/F 66. The memory control part 44 temporarily stores the data, which istaken in from the MEM 13, in the data buffer 62 by the data path controlpart 61, and transmits the data to a requesting channel via the accesscontrol part 41.

[0093] The VDC6 comprises, as shown in FIG. 6, a decoding part buffer71, a line buffer 72, a selector 73, a 9-line buffer 74, an image matrix75 of a 9-line×3 pixels, a jaggy correction part 76, a processing part77, an isolated point correction part 78, an error diffusion enhancement79 a dither smoothing part 80, an edge processing part 82 and a selector83. The jaggy correction part 76 is provided with a correction code part76 a and a RAM 76 b.

[0094] The VDC 6 decodes by the decoding part 71 3-bit encoding datatransmitted via the parallel bus 21 from the IMAC 12, and converts thedata into pixel data 2×2 pixels. The VDC 6 stores 2 pixels located inthe lower row of the converted pixel data in the 1-line buffer 72, andtransmits 2 pixels located in the upper row to the selector 73. Theselector 73 switches the decoded upper row pixels or lower row pixels insynchronization with a line synchronization signal, and transmits it tothe image matrix 75 through the 9-line buffer 74. The VDC 6 performs acontrol of switching the upper row pixel and the lower row pixel, asshown in FIG. 7. That is, the VDC 6 requests the IMAC 12 to transmit theencoded data for every two lines. At the first line, the decoded upperrow pixel is chosen as it is, and the 2 pixels of the lower row aretransmitted to the 1-line buffer 72. At the second line which indicatesthe next image line, the VDC 6 reads the previously stored lower rowpixels from the line buffer 72, and uses the pixels for pixelcorrection.

[0095] In addition, the code data treats the pixel information regardingtwo lines, and latter-part pixels are stored in the line memory whileprinting the head line. Accordingly, the transmission from IMAC 12 canbe performed every other line, and at a line which is not required totransmit, the MFP 1 opens the parallel bus 21 to other processing unitsso as to improve the data transmission efficiency of the MFP 1.

[0096] In the VDC 6, the image matrix 75 creates 13-pixel delay data inthe main scanning direction from data of nine lines, respectively, so asto create a 9-line×13-pixel two-dimensional matrix. Although the VDC 6accesses the matrix data simultaneously so as to carry out a binaryvalue/multi-value conversion processing, the VDC 6 performs, withrespect to an edge processing, a process with data on 1 line withoutusing a two-dimensional image matrix.

[0097] In the jaggy correction part 76 the correction code part 76 aperforms pattern matching using the arrangement data of the image matrix75 so as to generate 12-bit code data, and input the code data to theaddress of the RAM 76 b. The RAM 76 b is for image correction, andoutputs image correction data corresponding to an input code. It shouldbe noted that the correction data is separately downloaded to the RAM.

[0098] The isolated point correction part 78 detects an isolated pointby pattern matching in an image area of 9×13 containing an attentionpixel. By removing the pixel corresponding to an isolated point oradding pixels to the isolated point within two-dimensional range, theprocessing part 77 constitutes a set of pixels which are not isolatedand outputs the set of pixels to the selector 83. In addition, a modechange is available as to whether a masking is carried out by theprocessing part 77 or whether pixels are added to the circumference.That is, in a case of an isolated dot, depending on the processconditions of a write-in system, there may be a case in which a dot canbe reproduced and a case in which a dot cannot be reproduced, and, thus,unevenness occurs in concentration in an input concentration area, anddegradation of image quality is caused. Therefore, a mode change isperformed so as to not strike any dot or increase a dot density to therange in which dots can be reproduced stably. The isolated pointcorrection part 78 sets up a central pixel as an attention pixel withinthe range of the image matrix 75 of 9×13 in detection of an isolatedpoint. As an object of a judgment of whether to be an isolated pointregarding the attention pixel concerned, the isolated point correctionpart 78 judges relation to circumference pixels by pattern matching soas to judge an isolated point. The error diffusion enhancement part 79smoothes a texture by a band-pass filter holding a line image so as togenerate a phase signal based on the pixel row of the main scanningdirection, and outputs the phase signal to the selector 83.

[0099] The dither smoothing part 80 performs low path filter processingof 5×5, 7×7 and 9×9 on a binary value dither pattern so as toapproximately convert into a multi-value signal in false, and outputsthe dither pattern to the 2-dot processing part 81. Namely, by applyingeach smoothing filtering processes of 5×5, 7×7, and 9×9 to the9-line×13-pixel image matrix 75, the dither smoothing part 80 removes ahigh-band signal component from the input data which is a 1-bit binaryvalue signal, and outputs it to the 2-dot processing part 81.

[0100] The 2-dot processing part 81 performs equalization betweenadjacent pixels on the signal approximately multi-valued signal so as togenerate phase information, and outputs the phase information to theselector 83. That is, the 2-dot processing part 81 equalizes the pixels,which have been smoothed by the dither smoothing part 80, between EVENpixels and ODD pixels in the main scanning direction. A phase signal isdistinguished although this value is an average value. That is, an EVENpixel is made a right phase and an ODD pixel a left phase so as to form2-dot image data. Although the 2-dot processing part 81 outputs thephase data to the selector 83 as it is, the 2-dot processing part 81performs a level conversion on concentration data so as to convert intodata having a 4-bit width.

[0101] The selector 83 selects an image path according to the mode, andoutputs the data, which has been converted into a multi-value from abinary value, as 6-bit data having 4 bits for concentration and 2 bitsfor phase. The edge processing part 82 performs an edge smoothingprocessing on data on one line, and outputs the smoothed data to theselector 83. That is, the two-dimensional image matrix 75 is not neededfor the process in the edge processing part 82.

[0102] A description will now be given of an operation of the presentembodiment. The MFP 1 according to the present embodiment effectivelyuses the MEM 13 by sharing the MEM 13 with each unit.

[0103] That is, in the MFP 1, as shown in FIG. 6, the IMAC 12, the CDIC4 and the VDC6 are connected to the parallel bus 21, and datatransmission between the IMAC 12, the CDIC 4, and the VDC 6 is performedthrough the parallel bus 21. Moreover, the CDIC 4, the VDC 6, theprocess controller 8, etc., are connected to the serial bus 20, and datatransmission between the CDIC 4, the VDC 6, and the process controller 8is performed through the serial bus 20. Image data and a command codeare transmitted through the parallel bus 21 in a predetermined formatwithout discrimination. In the MFP 1, although the system controller 14manages the whole control, a direct control of functional modules otherthan a control of memory related units and the parallel bus 21 isperformed by the process controller 8. The process controller 8 iscontrolled by the system controller 14. The process controller 8 and thesystem controller 14 communicate with each other according to arelationship between a master and a slave. Format conversion betweenparallel data and serial data is performed in the CDIC 4 or the VDC 6.

[0104] The MFP 1 transmits a control signal of the system controller 14to the parallel bus 21 through the parallel bus control part 48 in theIMAC 12. After taking in the command data on the parallel bus 21, theCDIC 4 converts parallel data into serial data, and transmits theconverted data to the serial bus 20. The process controller 8 connectedto the serial bus 20 receives the command data, which is sent from thesystem controller 14, from the serial bus 20. The process controller 8controls the CDIC 4 and the VDC 6 via the serial bus 20 based oninstructions of the command data. The system controller 14 carries out asystem control independently from the process controller 8, while theprocess controller 8 controls the CDIC 4 or the VDC 6.

[0105] The MFP 1 has various functional modes, such as a copy mode, aprinter mode or a facsimile mode. In the printer mode, the MFP 1 servesas a connection composition as shown in FIG. 9. Namely, similar to thecase of FIG. 8, the IMAC 12 and the VDC 4, which are connected to thesystem controller 14, are connected to the parallel bus 21. The VDC 4and the process controller 8 are connected to the serial bus 20.Therefore, a scanner processing system does not need the CDIC 4.

[0106] In the printer mode, the MFP 1 supplies the image data forcarrying out a print output to the IMAC12 from the PC 30 connected tothe network NW or the general use serial bus 20. After image data isdeveloped on a bit map in the IMAC 12, the image data is transmittedfrom the IMAC 12 to the VDC 6 via the parallel bus 21. The MFP 1transmits a control command of the VDC 6 from the system controller 14to the VDC6 via the IMAC 12. After the control command is converted intoserial data in the VDC 6, the control command is transmitted to theprocess controller 8 via the serial bus 20. Then, MFP 1 shifts to awrite-in control by the process controller 8. The MFP 1 carries out acontrol based on a route as shown in FIG. 10. That is, the MFP 1 uses adata path of exclusive use without going the data transmission from theCDIC 4 to the VDC 6 via the parallel bus 21 so s to effectively use theparallel bus 21 and improve the performance of the entire MFP 1.Basically, the performance is improved by the role assignment betweenthe system controller 14 and the process controller 8. By the processcontroller 8 serving as a coprocessor of the system controller 14, awrite-in control and an image-processing control centering on theimaging unit 7 are performed. In performing a datacompression/decompression operation, as shown in FIGS. 11A and 11B, theMFP 1 performs a compression/decompression processing using thecompression/decompression part 45 of the IMAC 12, the data path controlpart 61 of the memory control part 44, and the DMAC 51. Thecompression/decompression part 45 is provided with a compressor 45 a anda decompressor 45 b, which are used by being switched betweencompression and decompression. The DMAC 51 is provided with the DMAC 51a for images and the DMAC 51 b for codes, which are used by beingswitched between compression and decompression. That is, the MFP 1avoids a collision of data on the DMAC 51 by using different channels ofthe DMAC 51 for the access to MEM 13 based on image data and code data.

[0107] When compressing image data (encoding), as shown in FIG. 11A, theMFP 1 takes in the image data from the MEM 13 by DMAC 51 a for imagesthrough the memory control part 44 and the access control part 41. TheMFP 1 compresses the image data by encoding by eliminating the redundantcorrelation information between pixels by the compressor 45 a of thecompression/decompression part 45. The MFP 1 transmits the encoded datato the DMAC 51 b for codes by the data path control part 61, and storesencoded data in the MEM 13 under the intervention of the memory controlpart 44 after an access control. When decompressing (decoding)compresses data, as shown in FIG. 11B, the MFP 1 takes in the encodeddata from the MEM 13 by the DMAC 51 b for codes through the memorycontrol part 44 and the access control part 41. The MFP 1 decompressesthe encoded data by encoding by complementing the correlationinformation between pixels by the decompressor 45 b. The MFP 1 transmitsthe decoded image data to the DMAC 51 a for images by the data pathcontrol part 61. After an access control, the MFP 1 stores the imagedata in the MEM 13 under the intervention of the memory control part 44,or transmits the image data to an external bus from the parallel buscontrol part 48, the network control part 47, or the serial port controlpart 49 without passing though the DMAC 51 a for images. When performingpixel density conversion, the MFP 1 shares the process to the IMAC 12and the system controller on the MEM 13 that is shared by the whole MFP1. A smoothing processing depending on a footer engine characteristic isassigned to the VDC 6. For example, when converting into a twice pixeldensity in each of the main scanning direction and the subscanningdirection by a pixel density conversion, the data to be subjected to thepixel density conversion may include read image data, facsimile data andthe digital data from the PC 30. In a case of read image data, the MFP 1performs a dot rearrangement after the density conversion by the IPP 5,which is a programmable operation processor, to the image datamaximum-quantized to the number of bits smaller than the number ofquantization bits by the SBU 3. In a case of facsimile data or imagedata from PC 30, the MFP 1 performs a dot rearrangement after performinga density conversion with respect to binary value data.

[0108] That is, in the case of the read image data, the MFP 1 quantizesthe analog data of an image, which is read by the light-receivingelement of the SBU 3, into 8-bit/pixel by the SBU 3, and applies animage processing by the IPP 5. In the MFP 1, although the IPP 5 performsa gradation processing such as an error diffusion processing so as toreconstruct an image according to an area gradation supposing a transferpaper output, a processing algorithm and a setting parameter are carriedout programmably, and an operation processing is performed so as toachieve a highest image quality and processing speed. The MFP 1quantizes the image data into 3-bit/pixel data having a small bit numberby the gradation processing of the IPP 5, and transmits the quantizeddata to the IMAC 12 via the CDIC through the parallel bus 21. Inaddition, it is assumed that the reading unit 2 is a device of 600 dpiin the main scanning direction and 600 dpi in the subscanning direction,and the imaging unit 7 has a high definition plotter printable by 1200dpi in the main scanning direction and 1200 dpi in the subscanningdirection. The MFP 1 accumulates the image data transmitted to the IMAC12 in the MEM 13.

[0109] As shown in FIG. 12A, a 600 dpi×600 dpi x×3 bits image isaccumulated in the MEM 13 managed by the IMAC 12 with respect to a sizeof an original to be read. It should be noted that FIG. 12A shows dataof a size of N pixel×N pixel. The IMAC 12 carries out a bit mapconversion so as to convert the bit map into a high definition densityof 1200 dpi×1200 dpi×1 bit, as shown in FIG. 12B. That is, in the imagedata of low resolution, 3 bits of concentration information of eachpixel are converted into a pixel density of high resolution. In thiscase, in response to an increase of the number of pixels, concentrationinformation is deleted and is converted into a binary value image. Itshould be noted that FIG. 12B shows an example in which an area of anoriginal the same as the bit map of FIG. 12A is converted intohigh-density data of 2N pixels×2N pixels, although the number of pixelsof FIG. 12A is merely increased in both the main scanning direction andthe subscanning direction. Moreover, the IMAC 12 performs a smoothingprocessing on the bit map stored in the MEM 13. FIG. 12C shows anexample in which a smoothing processing is applied to a binary value bitmap after the density conversion shown in FIG. 12B. In the smoothingprocessing, the binary value data is again converted into multi-valuedata so as to reproduce fine pixels.

[0110] It should be noted that, in FIG. 12C, thin black dots (circle ofhatching) indicate pixels interpolated by a pattern matching processingalthough consideration is not give to a multi value processing. A cornerof the central part, which is angled in FIG. 12B, is subjected to apattern matching processing so as to carry out a correction processingto form smooth edges.

[0111] In addition, when a record engine of the imaging unit 7 is alaser write-in type, a pulse width and a laser power to 1 pixel ischanged so as to carry out a multi-value writing in which an interval of1 pixel is divided. Thereby, the above-mentioned recording, whichcorrectly reproduces the bit map data which has been subjected to thepixel density conversion and the smoothing processing, can be performed.Moreover, in a case in which the imaging unit 7 corresponds to a recordengine which injects droplets of ink such as an inkjet printer, amulti-value level can be reproduced by recording an image by controllingan amount of ink.

[0112] The MFP 1 performs a density conversion also on facsimile data orbinary value data from the PC 30. Since gradation data is not assignedto 1 pixel with respect to the facsimile data or binary value data fromthe PC 30, dots are rearranged based on arrangement of circumferencepixels after carrying out a density conversion. However, practically,there is no problem even if simple expansion is applied in the mainscanning direction and the subscanning direction. Since ahigh-resolution processing with respect to edges is assigned to thesmoothing processing, there is no need to perform a pattern matchingprocessing in the IMAC 12, thereby carrying out a high-speed pixelconversion.

[0113] That is, supposing FIG. 12A shows a bit map of a binary valueimage of 600 dpi×600 dpi×1 bit from the PC 30, each pixel in the bit mapis simply doubled in both the main scanning direction and thesubscanning direction so s to convert into a pixel density of 1200dpi×1200 dpi×1 bit. With respect to the smoothing processing shown inFIG. 12C, similar to the read image data, the imaging unit 7 commonlyprocesses the image data irrespective of whether the image data is of acopy mode, a facsimile mode or a printer mode. After converting the bitmap on the MEM 13 into the output pixel density of the record engine ofthe imaging unit 7, the bit map data is treated as bit map dataindependent of the input device.

[0114] Density conversion and code assignment is performed in the dotprocessing, as shown in FIGS. 13 and 14. In the density conversion, acontrol of 1 dot corresponding to an isolated pint of which dotreproducibility depends on the record engine of the imaging unit 7 isassigned to the smoothing processing. Moreover, a dot arrangement isperformed by the density conversion so that an isolated 1 dot of whiteor black is not formed.

[0115] For example, when rearranging 1 pixel of 600 dpi to 4 pixels of1200 dpi, the 4 pixels are arranged in a square area so as to form 2×2pixels in the main scanning direction and the subscanning direction. Inthis case, there are only six arrangements of the dots which can betaken, that is, all white, all black and an arrangement in which a pairof two dots are formed. Two consecutive pixels in the a diagonaldirection shall not be permitted, and a control of 1-dot in each of themain scanning direction, the subscanning direction and the diagonaldirection is assigned to the smoothing processing.

[0116] A direction of connection of the pixels is beforehand taken intoconsideration at the time of the density conversion by the IMAC 12 sothat the pattern matching by the smoothing processing can be carried outeasily at a high speed. That is, in the original pixel of 600 dpi shownin FIG. 13, a code 0 is assigned to all whites, a code 5 is assigned toall blacks, and codes 1 to 4 are assigned to four kinds of arrangementof a pair of two pixels in vertical and horizontal directions.Therefore, the number of generated patterns after the density conversionis six, and all generation patterns can be represented by 3 bits. Changein the amount of data in this pixel density conversion is as follows.Namely, as for the read image data, image data corresponding to the sizeof a read original is transmitted to the IMAC 12 with a small value(less than 8 bits) from the IPP 5. With respect to the size of the readoriginal, a generated pattern is 600 dpi×600 dpi×3 bit, and the pixeldensity conversion with respect to the same size of the original becomes((1200 dpi×1200 dpi)/4)×3 bits. Here, the reason for dividing by “4” isto assign all 4 pixels to a 3-bit code.

[0117] If a ratio of the two above-mentioned equations is taken, theratio of the data transmitted to the VDC 6 from the MEM 13 to the datatransmitted to the MEM 13 from the IPP 5 becomes “1” which indicates thesame amount of data. As compared to a case where the converted data istransmitted to the VDC 6 as it is, the amount of data is reduced tothree quarters, thereby improving transmission efficiency. Therefore,when a small value level from the IPP 5 is greater than 3 bits, thetransmission efficiency from the MEM 13 to the VDC 6 is relativelyimproved. Moreover, although the transmission efficiency to the VDC 6deteriorates relatively when the small value level is less than 3 bits,the amount of data can be reduced to three quarters than a case in whichthe converted pixels of 1200 dpi×1200 dpi is transmitted without change.

[0118] The above-mentioned example is the case of read image data. In acase of facsimile data or print data from the PC 30, an amount of dataof the transmission code after pixel density conversion can be reducedto three quarters than directly transmitting the data, thereby improvingthe transmission efficiency.

[0119]FIG. 14 shows an example of a case in which a pattern matching iscarried out in a 3×3 pixel area of 600 dpi×600 dpi. In FIG. 14, athin-color pixel (pixel indicated by a hatched circle) positioned in thecenter of 3×3 pixels is an attention pixel. In FIG. 14, the attentionpixel is converted into 2×2 pixels of 1200 dpi×1200 dpi. That is, inFIG. 14, when the attention pixel is located on an edge and three pixelsexist on the right side, the attention pixel is converted into twopixels which are consecutively arranged in the right part in thevertical direction, and a code 2 is assigned thereto. When the attentionpixel is located on an edge and three pixels exist on the left side, theattention pixel is converted into two pixels which are consecutivelyarranged in the left part in the vertical direction, and a code 4 isassigned thereto. When the attention pixel is located on an edge andthree pixels exist on the lower side, the attention pixel is convertedinto two pixels which are consecutively arranged in the lower part inthe horizontal direction, and a code 3 is assigned thereto. When theattention pixel is located on an edge and three pixels exist on theupper side, the attention pixel is converted into two pixels which areconsecutively arranged in the upper part in the horizontal direction,and a code 1 is assigned thereto. When the attention pixel is located asa convex pixel in any directions, the attention pixel is converted intoall black pixels, and a code 5 is assigned thereto. When the attentionpixel is located as a concave pixel in any directions, the attentionpixel is converted into all white pixels, and a code 0 is assignedthereto. It should be noted that these patterns are examples and a codeis assigned to each of pixel arrangements which can be formed. A pixeldensity conversion is performed by the system controller 14 with respectto image data in the MEM 13 by referring to corresponding pixels bymemory access of the IMAC 12.

[0120] In the above-mentioned data processing, data transmission isperformed along the path course of data transmission shown in FIGS. 15and 16. FIG. 15 shows the data transmission path in the case of thepixel density conversion and the edge smoothing processing applied tothe read image data, which is an example of 600 dpi read and 1200 dpiwrite.

[0121] In the case of read image data, as indicated by a datatransmission path (1) shown in FIG. 15, the read image data of 600dpi×600 dpi, which is read by the light-receiving element of the SBU 3and is converted into digital data, is transmitted to the IPP 5. In theIPP 5, the read image data is re-quantized into a small value of 3bits/pixel. The quantized data is stored in the MEM 13 via the CDIC 4,the parallel bus 21 and the IMAC 12. In the IMAC 12 and the systemcontroller 14, the read image data stored in the MEM 13 isdensity-converted into a binary value image of 1200 dpi×1200 dpi in theIMAC 12 and the system controller 14, and a code of 3 bits is assigned.The above processing is performed so as to grouping four pixels andassign a code, and the amount of data is reduced rather than directlytreating as bit data. As indicated by a data transmission path (2) shownin FIG. 15, the converted data is transmitted from the MEM 13 to the VDC6 via the IMAC 12, the parallel bus 21 and the CDIC 4. In theabove-mentioned data transmission, there is no change in the amount ofdata on the data transmission course (1), and the transmissionefficiency of the parallel bus 21 does not decrease due to a highlydensification. Then, as mentioned above, the code data transmitted tothe VDC 6 is decoded in the VDC 6. Then, after correcting the image datato a high print quality by applying the edge smoothing, the recordoutput of the image is carried out by the imaging unit 7.

[0122]FIG. 16 shows a data transmission path in a case in which binaryimage data, which is facsimile data or print data from the PC 30, issubjected to a density conversion. In the case of binary value imagedata, as indicated by a data transmission path (3) shown in FIG. 16, thefacsimile received binary value image data is developed on the MEM 13via the IMAC 12. On the other hand, the print data from PC 30 isdeveloped on the MEM 13 via the IMAC 12, as indicated by a datatransmission path (4) shown in FIG. 16. The binary value bit map datadeveloped on the MEM 13 via the data transmission path (3) or (4) isdensity-converted into 1200 dpi×1200 dpi which is the resolution of therecord engine of the imaging unit 7. In this case, the image data isconverted into code data corresponding to two consecutive pixels whichdoes not generate an isolated single dot of white or black so as toreduce the amount of data transmitted to the parallel bus 21. The bitmap data is transmitted from the MEM 13 to the VDC 6 through theparallel bus 21, as indicated by a data transmission path (5) shown inFIG. 14. The VDC 6 decodes the transmitted code data, and performs anedge smoothing processing on the binary value bit map image so as tocarry out a record output by the imaging unit 7.

[0123] Thus, MFP 1 according to the present embodiment temporarilystores in the MEM 13 the digital image signal, which is generated byconverting read image data of an original into digital data, or thedigital image signal which is generated digitally. The, the image signalstored in the MEM 13 is processed to generate an output image signal,which can be record output by a write-in control of the imaging unit 7.At this time, an access of the digital image signal to the MEM 13 istotally managed. Moreover, when a pixel density conversion is performedto increase a pixel density of the digital image signal stored in theMEM 13, the amount of transmission data is reduced.

[0124] Therefore, the central-controlled MEM 13 is shared by a pluralityof functions, which results in an effective use of the MEM 13. Moreover,the density conversion can be carried out so that the converted datamatches the pixel density. Moreover, resources can be used effectivelyby an inexpensive and small MFP 1, and a high-definition image can begenerated.

[0125] Moreover, the MFP 1 according to the present embodiment storesimage data in the MEM 13 after applying an arbitrary process to thedigital image signal, which is read from an original and digitallyconverted, by the IPP 5 which is a programmable operation processor soas to change the read image data to the number of quantization stepsless than the number of read quantization when reading Therefore, animage quality can be improved by applying an arbitrary process to theread image data, and also the data transmission efficiency to the MEM 13can be improved.

[0126] Furthermore, when the MFP 1 according to the present embodimentconverts a low-density single dot into a plurality of high-densitypixels, the MFP 1 arranges the converted high-density pixels in a squarearea while preventing generation of an isolate black or white pixel.Therefore, the number of pixels in the main scanning direction and thesubscanning direction can be increased simultaneously, and a high pixeldensity conversion of high conversion efficiency can be achieved.

[0127] Moreover, the MFP 1 according to the present embodiment separatesmutually pixel density conversion processing, which converts a pixeldensity of a digital image signal, and the edge smoothing processing,which smoothes an edge of black pixels and white pixels, and performsthe pixel density conversion processing on the MEM 13, and performs theedge smoothing processing by a write-in control of the imaging unit 7.Therefore, the smoothing processing and pixel density conversiondepending on the characteristic of the imaging unit 7 can be carried outindependently, and processing time for the pixel density conversion canbe shortened. Thereby, a higher definition image can be promptlygenerated.

[0128] Furthermore, the MFP 1 according to the present embodimenttransmits image data in the state code data from the MEM 13 to theimaging unit 7 and reverse-converts the image data into pixel data inthe imaging unit 7, and, thereafter, the pixel data is record output byperforming a write-in control. Therefore, the data transmission from theMEM 13 to the imaging unit 7 can be more efficiently performed in ashort time.

[0129] Moreover, a data bus can be effectively used so as to achievemore efficient process at a higher speed. Moreover, the MFP 1 accordingto the present embodiment transmits the code data, which is to betransmitted from the MEM 13 to the imaging unit 7, by reading from theMEM 13 in synchronization with a signal indicating a writing line of thecode data concerned. Therefore, since data can be transmitted accordingto a request of the imaging unit 7 only when required, a bus occupancytime can be shortened and the whole use efficiency and whole bus useefficiency of the MEM 13 can be improved.

[0130] Furthermore, programs of the above-mentioned image-processingmethod is recordable on a recording medium such as a CD-ROM. The programof the image-processing method may be read from a recording medium by acomputer connected to the serial bus 20 shown in FIG. 3. Thus, thecentral-managed MEM 13 is shared by a plurality of functions so as toeffectively use the MEM 13, and the MFP 1 can be constructed to performa density conversion so as to match a pixel density.

Second Embodiment

[0131] A description will now be given, with reference to FIGS. 17through 22, of an image-processing apparatus and method according to asecond embodiment of the present invention. The image-processingapparatus according to the present embodiment has the same wholecomposition as the image-processing apparatus according to the firstembodiment, and a description thereof will be omitted.

[0132]FIG. 17 is a block diagram showing an outline composition of aframe memory and an image memory access control part (IMAC) according tothe present embodiment. In FIG. 17, data output from a data control part91 of the CDIC 4 is supplied to the IMAC 12, which is a memorycontroller, via the parallel bus 21 such as a PCI bus. The IMAC 12 isprovided with a high-density conversion part 12a and a code conversionpart 82. The high-density conversion part 12a converts imaged data of Mdpi/N values sent from the data control part 91 into image data of astill higher-density of m dpi/n values (M<m, N>n). The code conversionpart 82 performs a code conversion process of data from the MEM 13.

[0133] A description will be given, as an example of a pixel densityconversion according to the present embodiment, of a case where adensity conversion of the data of 600 dpi/5 values into data of 1200dpi/2 values is performed.

[0134] The binary value data after density conversion is stored in theMEM 13, which consists of a frame memory. When the image data stored inthe MEM 13 is read and transmitted through the PCI bus again, atransmission efficiency is raised by encoding image data so as to reducethe amount of data.

[0135]FIG. 18 is an illustration showing a processing operation of ahigh-density conversion part 12A in the IMAC 12. In FIG. 18, since thedata is equivalent to a half dot when the data transmitted from a datacontrol part 4A is 2 of 5-value data, four patterns (3 a-3 d) can betaken as a pattern. However, since a dot position control is notperformed here, the data is converted into 4-bit data as it is, and isstored in the MEM 13.

[0136]FIG. 19 is an illustration showing a processing operation of acode conversion part 12B in the IMAC 12. In FIG. 19, considering thearrangement of the data stored in the MEM 13, there are patterns a-d inaccordance with each size. However, there is a regularity in the dotposition control, and when a pixel is enlarged by a dot concentrationmethod so as to strike the dot stably, there is considered a patternindicated by 401. In this example of the regularity, P corresponds to asingle pixel of 600 dpi, and it is represented to enlarge the pixelsfrom positions of d, c, a and b, in that order, when the pixel of 600dpi is divided into four pixels of 1200 dpi and strike each dot at aquarter power. That is, since the position from which a strike a pixelis started is decided by the position of the input image data, the code,which the IMAC 12 supplies, is merely related with the size of data.Therefore, what is necessary is to encode only five patterns (3 bits) ofa instead of 14 patterns (4 bits) including the original patterns of a,b, c and d. Thus, the amount of data, which is transmitted through thebus, decreases, and its transmission efficiency improves.

[0137]FIG. 20 is an illustration showing another processing operation ofthe code conversion part in the IMAC 12. As indicated by 501, thisexample is a case where a strike of dot is started at the same positionin every position, which is an advantageous dot formation method toexpress a high resolution for a thin line or the like. Also in thiscase, in order to perform a code conversion by a code conversion part12B, only five code patterns (3 bits) are required. Furthermore, thereis no need to decide a position from which a dot strike is startedaccording to the image data position.

[0138]FIG. 21 is a block diagram showing an example of a composition inthe case of changing pixel arrangement according to an image dataposition. In FIG. 21, the data operation part 92 and CDIC 4 are added inaddition to the composition shown in FIG. 17. The code data reduced mostefficiently is transmitted to the CDIC 4 through the PCI bus (parallelbus 21). The code-is developed to data by deciding whether to change thepixel arrangement for each position according to information (forexample, 1-bit information indicating whether it is an edge or non-edge)separately sent from the IPP 5.

[0139]FIG. 22 is an illustration showing an example of the developmentof data encoded as mentioned above. As shown in FIG. 22, although “1110”is obtained if the code is 3 and is developed as it is, a position isshifted so as to obtain “1011” only when a conversion control isperformed. In FIG. 22, when the pixel is arranged by the pattern of c,“1011” is obtained by starting a reading operation of 4-bit “1110” datafrom the position of c.

[0140] It should be noted that process programs for performing theabove-mentioned process may be stored in a recording medium such as aCD-ROM, which is readable by a computer connected via the serial bus 20as shown in FIG. 3. Moreover, the process programs may be stored in theROM 10.

[0141] The present invention is not limited to the specificallydisclosed embodiments, and variations and modifications may be madewithout departing from the scope of the present invention.

[0142] The present application is based on Japanese priorityapplications No. 2000-29863 filed on Sep. 29, 2000, No. 2000-294698filed on Sep. 27, 2000 and No. 2001-266382 file on Sep. 3, 2001, theentire contents of which are hereby incorporated by reference.

What is claimed is:
 1. An image-processing apparatus comprising: amemory storing a digital image signal; a memory access control partentirely managing all accesses to said memory with respect to thedigital image signal; and an image processing part converting thedigital image signal stored in said memory into an output image signalto be supplied to an imaging unit outputting a visible image based onthe output image signal so that a pixel density of the output imagesignal is higher than a pixel density of the digital image signal readfrom said memory and an amount of the output image signal is less thanan amount of the digital image signal stored in said memory.
 2. Theimage-processing apparatus as claimed in claim 1, further comprising aprogrammable operation processor processing the digital image signal soas to reduce a number of quantization steps of the digital image signaland store the digital image signal having a reduced number ofquantization steps in said memory.
 3. The image-processing apparatus asclaimed in claim 1, wherein said memory access control part arrangespixels of the output image signal in a square area while preventinggeneration of an isolated single pixel of black or white when convertingthe digital image data into the output image data.
 4. Theimage-processing apparatus as claimed in claim 1, wherein said memoryaccess control part includes a pixel density conversion part convertingthe digital image signal by using said memory; and said image processingpart includes an edge smoothing part smoothing an edge of black pixelsand white pixels, wherein said edge smoothing part is controlled,separately from said pixel density conversion part, by a write-incontrol performed by said imaging unit.
 5. The image-processingapparatus as claimed in claim 1, wherein the output image signal istransmitted from said memory to said imaging unit in a form of codedata, and said imaging unit converts the code data into pixel data so asto perform an image output under the write-in control of said imagingunit.
 6. The image-processing unit as claimed in claim 5, whereintransmission of the code data from said memory to said imaging unit isperformed in synchronization with a signal indicating a write-in line ofthe code data.
 7. An image-processing method comprising the steps of:storing a digital image signal in a memory; entirely managing allaccesses to said memory with respect to the digital image signal; andconverting the digital image signal stored in said memory into an outputimage signal to be supplied to an imaging unit outputting a visibleimage based on the output image signal so that a pixel density of theoutput image signal is higher than a pixel density of the digital imagesignal read from said memory and an amount of the output image signal isless than an amount of the digital image signal stored in said memory.8. A processor readable medium storing program code for causing animage-processing apparatus to perform an image processing, comprising:program code means for storing a digital image signal in a memory;program code means for entirely managing all accesses to said memorywith respect to the digital image signal; and program code means forconverting the digital image signal stored in said memory into an outputimage signal to be supplied to an imaging unit outputting a visibleimage based on the output image signal so that a pixel density of theoutput image signal is higher than a pixel density of the digital imagesignal read from said memory and an amount of the output image signal isless than an amount of the digital image signal stored in said memory.9. An image-processing apparatus having a frame memory controlled by amemory controller, comprising: a scanner reading an image so as toproduce read image data; a pixel density conversion part converting theread image data into high-density image data having a pixel densityhigher than a pixel density of the read image data; a memory storing thehigh-density image data according to a predetermined arrangement ofpixels; a code conversion part converting the high-density image datainto code data according to a predetermined conversion code; and anoutput interface part outputting code data as image data to an imagingunit forming a visible image based on the image data.
 10. Theimage-processing apparatus as claimed in claim 9, wherein said codeconversion part decides an ON/OFF position of pixel data of the imagedata output from said output interface part, and said output interfacepart changes pixel positions of the high-density image data based onpixel positions of the read image data.
 11. The image-processingapparatus as claimed in claim 9, wherein said code conversion part setsthe pixel positions of the high-density image data based on informationregarding characteristics of the read image data.
 12. Animage-processing method comprising the steps of: reading an image so asto produce read image data; converting the read image data into ahigh-density image data having a pixel density higher than a pixeldensity of the read image data; storing the high-density image data in amemory according to a predetermined arrangement of pixels; convertingthe high-density image data into code data according to a predeterminedconversion code; and outputting code data as image data to an imagingunit forming a visible image based on the image data.
 13. Theimage-processing method as claimed in claim 12, wherein the step ofconverting the high-density image data includes a sep of deciding anON/OFF position of pixel data of the image data, and the step ofoutputting code data includes a step of changing pixel positions of thehigh-density image data based on pixel positions of the read image data.14. The image-processing method as claimed in claim 12, wherein the stepof converting the high-density image data includes a step of setting thepixel positions of the high-density image data based on informationregarding characteristics of the read image data.
 15. A processorreadable medium storing program code for causing an image-processingapparatus to perform an image processing, comprising: program code meansfor reading an image so as to produce read image data; program codemeans for converting the read image data into a high-density image datahaving a pixel density higher than a pixel density of the read imagedata; program code means for storing the high-density image data in amemory according to a predetermined arrangement of pixels; program codemeans for converting the high-density image data into code dataaccording to a predetermined conversion code; and program code means foroutputting code data as image data to an imaging unit forming a visibleimage based on the image data.
 16. The processor readable medium asclaimed in claim 15, wherein the program code means for converting thehigh-density image data includes program code means for deciding anON/OFF position of pixel data of the image data, and the program codemeans for outputting code data includes program code means for changingpixel positions of the high-density image data based on pixel positionsof the read image data.
 17. The processor readable medium as claimed inclaim 15, wherein the program code means for converting the high-densityimage data includes program code means for setting the pixel positionsof the high-density image data based on information regardingcharacteristics of the read image data.